Sulfonic Esters Of Metal Oxides And Methods Of Their Use

ABSTRACT

The present invention is directed to sulfonic esters of metal oxides including those of formulas I and II:

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 14/178,592, filed Feb.12, 2014, which claims the benefit of U.S. Provisional Application No.61/764,127, filed Feb. 13, 2013, the entireties of which areincorporated by reference herein.

TECHNICAL FIELD

The present invention is directed to sulfonic esters of metal oxides andtheir uses.

BACKGROUND

Corroles are tetrapyrrolic macrocycles:

Corroles are becoming increasing useful in the field of chemicalsynthesis as catalysts in, for example, oxidation, hydroxylation,hydroperoxidation, epoxidation, sulfoxidation, reduction, and grouptransfer reactions. See, e.g., Aviv, I., Gross, Z., Chem. Commun., 2007,1987-1999. Based on their physico-chemical properties, it is envisionedthat corroles could be useful in the sensors field and biomedical field.Id. Corrole-based materials useful in the chemical synthesis, sensor,biomedical, and other fields are needed.

SUMMARY

The present invention is directed to materials of formula I:

wherein A is a corrolyl or metallated corrolyl; M is a surfacecomprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO,Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0or 1.

The invention is also directed to materials according to formula II:

wherein B is —NCO, C₁₋₁₀alkyl, or

wherein R¹ is —COOH, —COOC₁₋₆alkyl, C₁₋₆alkyl, or aryl optionallysubstituted with halogen or C₁₋₆alkyl; M is a surface comprising TiO₂,BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO,Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO; and n is 0 or 1.

Methods of making materials of formulas I and II are described herein.Also described are methods of using the materials of the invention inapplications such as optical imaging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts confocal fluorescence microscopy images of 1-TiO₂ [(a),(b), (c)], 1-Al—TiO₂ [(d), (e), (0], and 1-Ga—TiO₂ [(d), (e), (f)].

FIG. 2 depicts transmission electron microscopic (TEM) images of TiO₂nanoparticles of the invention before and after dye-functionalization.(a and d) Images of the initial TiO₂ nanoparticles. (b and e) Images ofthe nanoparticles after peroxide-etching. (c and f) Images of thenanoparticles after dye functionalization. The scale bar is 25 nm forthe top row and 100 nm for the bottom row of images.

FIG. 3 depicts electronic absorption spectra for an amphiphilic corrole(H₃tpfc(SO₂OH)₂) and corrole-TiO₂ nanoconjates of the invention inphosphate buffer saline pH 7.4.

FIG. 4 depicts confocal fluorescence microscopic images of U87-Luc cellstreated with 0.2 μg/mL of a preferred embodiment of the invention(1-Al—TiO₂) after 24 h (a), 48 h (b), and 72 h (c).

FIG. 5 depicts Z-stacked confocal fluorescence micrographic images ofindividual U87-Luc cells taken at 0.5-μm slice intervals after (a) 48 hand (b) 72 h of treatment with 0.2 μg/mL of a preferred embodiment ofthe invention (1-Al—TiO₂).

FIG. 6 depicts a cell viability plot of U87-Luc cells treated by of apreferred embodiment of the invention (1-Al—TiO₂) at variousconcentrations (2 ng/mL to 2 mg/mL) using a bioluminescence assay.

FIG. 7 depicts the results of mouse primary hepatocytes (MPH) treatedwith a preferred embodiment of the invention (1-Al—TiO₂) in variousconcentrations (0.3 ng/mL to 0.3 mg/mL) for 24 and 48 h.

FIG. 8 depicts ATR-IR spectra for TiO₂ nanoparticles and preferredmaterials of the invention.

FIG. 9 depicts normalized ATR-IR spectra for TiO₂ nanoparticles andpreferred materials of the invention.

FIG. 10 depicts X-ray photoelectron spectra for nanoconjugates 1-TiO₂,1-Al—TiO₂, and 1-Ga—TiO₂ exhibiting the F(1s) band.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention is directed to materials, preferablynanoparticulate materials, comprising a metal oxide covalently bonded toa corrole or metallated-corrole through an —SO₂— linkage. The metaloxides for use in making the materials of the invention include thosehaving at least one —OH group. Such metal oxides are known in the artand are described in further detail below.

One embodiment of the invention is directed to materials according toformula I:

wherein A is a corrolyl or metallated corrolyl;M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂,CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO;andn is 0 or 1.

Within the scope of the invention, M is a surface that comprises a metaloxide, for example, a metal oxide that comprises at least one —OH group.The —OH group can be inherently present on the surface. Alternatively,the at least one —OH group can be incorporated by oxidizing the surfacewith a reagent such as hydrogen peroxide. Preferred surfaces for use inthe invention include metal oxides such as TiO₂, BaTiO₃, SnO₂, Al₂O₃,Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO,SnO₂, SiO₂, and ZnO. In some embodiments, the surface comprises TiO₂. Insome embodiments, the surface comprises BaTiO₃. In some embodiments, thesurface comprises SnO₂. In some embodiments, the surface comprisesAl₂O₃. In some embodiments, the surface comprises Fe₂O₃. In someembodiments, the surface comprises Fe₃O₄. In some embodiments, thesurface comprises ZrO₂. In some embodiments, the surface comprises CeO₂.In some embodiments, the surface comprises CdO. In some embodiments, thesurface comprises Cr₂O₃. In some embodiments, the surface comprises CuO.In some embodiments, the surface comprises MnO. In some embodiments, thesurface comprises Mn₂O₃. In some embodiments, the surface comprisesMnO₂. In some embodiments, the surface comprises NiO. In someembodiments, the surface comprises SnO. In some embodiments, the surfacecomprises SnO₂. In some embodiments, the surface comprises SiO₂. In someembodiments, the surface comprises ZnO.

In preferred embodiments, the surface is a nanoparticle surface.

In some embodiments, n is 0. In other embodiments, n is 1.

Corroles for use in the invention are known in the art and are of thegeneral formula:

The corroles of the invention described herein can be attached to theM-OSO₂-moiety(ies) of the invention through any available carbon.

Particularly preferred corroles for use in the invention include thoseof the following general formula:

wherein Ar is an aryl group, for example, a phenyl or naphthyl group. Insome embodiments of the invention, the aryl group is unsubstituted. Inother embodiments, the aryl group is substituted. For example, when thearyl group is phenyl, the phenyl can be optionally substituted withhalogen, for example, 1 to 5 halogen, that is, one or more of F, Cl, Br,or I, with F being a particularly preferred halogen. In exemplaryembodiments, the aryl group is pentafluorophenyl. In other embodiments,when the aryl group is naphthyl, the naphthyl can be optionallysubstituted with 1 to 7 halogen, with F being a particularly preferredhalogen.

Preferred corrolyls for use in the invention are those wherein Ar ispentafluorophenyl and include

In addition to being substitued with one or more halogens, the arylgroup can be further substituted with —NR³R⁴, wherein R³ and R⁴ are eachindependently H, C₁₋₁₀alkyl, C₁₋₁₀alkenyl, or -alkaryl; or R³ and R⁴,together with the nitrogen atom to which they are attached, form aheterocycloalkyl ring, which may be optionally substituted withC₁₋₆alkyl, for example, methyl or ethyl. Examples of —NR³R⁴ moietiesinclude:

Corroles incorporating an —NR³R⁴ substituted aryl group can be accessedusing methods known in the art, for example, using nucleophicsubstitution reactions. See, e.g., Hori, T., Osuka, A. Eur. J. Org.Chem. 2010, 2379-2386. For example, corroles incorporating an —NR³R⁴substituted aryl group can be accessed using the following syntheticscheme:

Amines that can be used in nucleophilic substitution reactions include,for example, benzylamine, octylamine, sec-butylamine, allylamine,dimethylamine, morphiline, piperidine, and N-methylpiperazine.

Another preferred corrole for use in the invention is of the generalformula

wherein each R² is independently H, C₁₋₆alkyl, halogen, or M-O—SO₂—,wherein M is as described above.

Yet another preferred corrole for use in the invention is of the generalformula

wherein Ar and R² are as previously described.

Corroles for use in the invention can also be metallated. In metallatinga corrole, the nitrogens of the corrole are coordinated to a metal.Metals for use in the metallated corroles of the invention include anymetal known in the art to be useful for coordinating to a corrole. Thoseof skill in the art understand that the function and use of the corrolecan be modified by changing the coordinated metal.

For example, metals for use in metallating the corroles of the inventioninclude Al, Ga, Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge,Ti, and Mo. Particularly preferred metals include Al and Ga. Anotherpreferred metal is Fe. Yet another preferred metal is Mn. Another metalfor use in the invention is Sb. Another metal for use in the inventionis Co. Another metal for use in the invention is Cr. Another metal foruse in the invention is Rh. Another metal for use in the invention isRu. Another metal for use in the invention is Ro. Another metal for usein the invention is Ir. Another metal for use in the invention is V.Another metal for use in the invention is Re. Another metal for use inthe invention is Cu. Another metal for use in the invention is Sn.Another metal for use in the invention is Ge. Another metal for use inthe invention is Ti. Another metal for use in the invention is Mo.

The metals for use in metallating the corroles of the invention can beoptionally coordinated to one or more ligands. Such ligands are known inthe art and include, for example, pyridine, nitrosyl, imido, nitrido,oxo, ether, hydroxyl, chloride, carbonyl, fluoro, bromo, phenyl, iodo,phosphine, arsine, and the like. Those skilled in the art would readilybe able to determine a suitable ligand for any particular metal. Aparticularly preferred ligand for use in the invention is pyridine.Preferred metal-ligand moieties include Al(ligand)₂ and Ga(ligand), withAl(pyridine)₂ and Ga(pyridine) being particularly preferred.

Exemplary materials of formula I according to the invention include:

wherein Ar is pentafluorophenyl. In particularly preferred embodiments,Ar is pentafluorophenyl and M is TiO₂.

While 2,17 substituted corroles have been set forth herein, theseexamples are exemplary only and are not meant to limit the invention. Itis envisioned that substitution at any position of the corrolyl ormetallated corrolyl is within the scope of the invention.

Materials of formula I can be made according to the following method:contacting a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄,ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, orZnO, the surface having at least one —OH group, with a compound offormula III:

(Cl—SO₂)_(m)-A  (III)

wherein A is corrolyl or metallated corrolyl; and

wherein m is 1 or 2.

Preferably, the synthetic methods of the invention are conducted in anorganic solvent such as pyridine, with heat.

Compounds of formula III can be prepared according to methods known inthe art. See, e.g., (a) Mahammed, A.; Goldberg, I.; Gross, Z. Org. Lett.2001, 3, 3443. (b) Saltsman, I.; Mahammed, A.; Goldberg, I.; Tkachecko,E.; Botoshansky, M.; Gross, Z. J. Am. Chem. Soc. 2002, 124, 7411. Seealso, Blumenfeld, C. M.; Grubbs, R. H.; Moats, R. A.; Gray, H. B.;Sorasaenee, K. Inorg. Chem. 2013, 52, 4774. One exemplary method ofpreparing compounds of formula III is shown in Scheme 1.

The corrole or metallated corrole used in any of the methods ofpreparing materials of formula I can be any of the corroles ormetallated corroles described herein.

In preferred methods of the invention, the surface is a nanoparticlesurface. In other preferred methods of the invention, the surfacecomprises TiO₂.

Corrole coupling to the metal oxide surfaces of the invention can beperformed by mixing metals of the invention bearing hydroxylatedsurfaces, preferably in nanocrystal form, with solutions of corrole andheating, preferably to reflux. After repeated washing with copiousamounts of solvent such as, for example, CH₂Cl₂, acetone, and water, anddrying under vacuum, powders are obtained.

Preferred corroles for use in the methods of making materials of formulaI include:

wherein Ar and R² are as set forth above.

Preferred metallated corroles for use in the methods of the inventioninclude:

wherein Ar and R² are as set forth herein above and wherein D is Al, Ga,Fe, Mn, Sb, Co, Cr, Rh, Ru, Ro, Ir, V, Re, Cu, Sn, Ge, Ti, or Mo, eachof which is optionally coordinated to one or more ligands. In preferredembodiments, D is Al(pyridine)₂ or Ga(pyridine).

The materials of the invention can be use in synthetic, biomedical, andoptical imaging applications. In a preferred embodiment of theinvention, the materials of formula I are used in imaging cancer in apatient. For example, a material according to formula I, wherein A is ametallated corrolyl, is administered to a patient. After a period oftime sufficient for the material to be taken up by any cancer cells, thecancer cells within the patient are imaged using optical imaging,preferably using fluorescence imaging. Cancers that can be imaged usingthe methods of the invention will include glioblastoma, melanoma, breastcancer, liver cancer, and colon cancer.

Preferably, the materials used in the imaging methods of the inventioninclude

wherein Ar is pentafluorophenyl and M is preferably TiO₂.

The materials of formula I of the invention can also be useful in otherfields of endeavor by changing the coordinating metal in the metallatedcorrole. For example, materials of the invention can be useful in thehydroxylation and hydroperoxidation of alkanes. The materials of theinvention are also useful in epoxidation and sulfoxidation reactions.The materials of the invention are also useful in catalysis, forexample, reduction and group transfer catalysis.

In other embodiments, the materials of formula I of the invention areuseful in corrole-based sensing applications and dye-sensitized solarcells. In other embodiments, the materials of formula I of the inventionwill have anticancer activity or will prevent cell death. In otherembodiments, the materials of the invention are useful in singlet oxygensensitization. In other embodiments, the materials of the invention areuseful in lipo-protein protection and neuroprotection.

The invention is also directed to materials according to formula II:

wherein B is —NCO, C₁₋₁₀alkyl, or

wherein R¹ is —COOH, —COOC₁₋₆alkyl, C₁₋₆alkyl, or aryl optionallysubstituted with halogen or C₁₋₆alkyl;

M is a surface comprising TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂,CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, or ZnO;and

n is 0 or 1.

Within the scope of the invention, M is a surface that comprises a metaloxide, for example, a metal oxide that comprises at least one —OH group.The —OH group can be inherently present on the surface. Alternatively,the at least one —OH group can be incorporated by oxidizing the surfacewith a reagent such as hydrogen peroxide. Preferred surfaces for use inthe invention include TiO₂, BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂,CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO, SnO, SnO₂, SiO₂, and ZnO.In some embodiments, the surface comprises TiO₂. In some embodiments,the surface comprises BaTiO₃. In some embodiments, the surface comprisesSnO₂. In some embodiments, the surface comprises Al₂O₃. In someembodiments, the surface comprises Fe₂O₃. In some embodiments, thesurface comprises Fe₃O₄. In some embodiments, the surface comprisesZrO₂. In some embodiments, the surface comprises CeO₂. In someembodiments, the surface comprises CdO. In some embodiments, the surfacecomprises Cr₂O₃. In some embodiments, the surface comprises CuO. In someembodiments, the surface comprises MnO. In some embodiments, the surfacecomprises Mn₂O₃. In some embodiments, the surface comprises MnO₂. Insome embodiments, the surface comprises NiO. In some embodiments, thesurface comprises SnO. In some embodiments, the surface comprises SnO₂.In some embodiments, the surface comprises SiO₂. In some embodiments,the surface comprises ZnO.

In preferred embodiments, the surface is a nanoparticle surface.

In some embodiments, n is 0. In other embodiments, n is 1.

In certain embodiments, B is —NCO.

In other embodiments, B is C₁₋₁₀alkyl, for example methyl, ethyl,propyl, butyl, sec-butyl, tert-butyl, pentyl, and the like.

In yet other embodiments, B is

wherein R¹ is —COOH, —COOC₁₋₆alkyl; C₁₋₆alkyl; or aryl optionallysubstituted with halogen or C₁₋₆alkyl.

In some embodiments, B is

wherein R¹ is —COOH.

In other embodiments, B is

wherein R¹ is —COOC₁₋₆alkyl, for example, —COOMe, —COOEt, —COOPr,—COOBu, and the like.

In other embodiments, B is

wherein R¹ is C₁₋₆alkyl, for example, methyl, ethyl, propyl, butyl,sec-butyl, tert-butyl, pentyl, and the like.

In yet other embodiments, B is

wherein R¹ is aryl, for example, phenyl or naphthyl. In theseembodiments, the aryl can be optionally substituted with one or moresubstitutents selected from the group consisting of halogen andC₁₋₆alkyl.

In those embodiments wherein B is

B is preferably

Methods of making materials of formula II are also within the scope ofthe invention. According to the invention, materials of formula II canbe prepared by contacting a surface comprising TiO₂, BaTiO₃, SnO₂,Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO, Mn₂O₃, MnO₂, NiO,SnO, SnO₂, SiO₂, or ZnO, the surface having at least one —OH group, witha compound of formula IV:

Cl—SO₂—R  (IV)

wherein R is —NCO or

wherein R¹ is —C(O)OH, —C(O)OC₁₋₆alkyl;C₁₋₆alkyl; or aryl optionally substituted with halogen or C₁₋₆alkyl.

Compounds of formula IV can be prepared using methods known in the art.

Materials of formula II are useful in the field of chemical synthesis,for example, as catalysts. Materials of formula II are also useful inthe field of material science.

As used herein, the term “halogen” refers to F, Cl, Br, or I.

As used herein, “alkyl” refers to branched or straight-chain saturatedaliphatic hydrocarbon groups having the specified number of carbonatoms. For example, C₁₋₁₀alkyl denotes an alkyl group having 1 to 10carbon atoms. Preferred alkyl groups include methyl, ethyl, propyl,butyl, sec-butyl, tert-butyl, pentyl, hexyl, and the like.

As used herein “alkenyl” refers to hydrocarbon chains that include oneor more double bonds.

As used herein, “aryl” refers to phenyl or naphthyl.

As used herein, “alkaryl” refers to an aryl moiety attached through analkylene group, for example, benzyl (—CH₂-phenyl).

As used herein, “heterocycloalkyl” refers to a 5 to 7-memberedmonocyclic or bicyclic saturated ring that includes at least oneheteroatom that is N, O, or S. Examples include piperidinyl,piperazinyl, morpholinyl, and pyrrolidinyl.

As used herein, “corrolyl” refers to a corrole moiety.

The following examples are presented in order to more fully illustratethe preferred embodiments of the invention. They should in no way beconstrued, however, as limiting the broad scope of the invention.

EXPERIMENTAL SECTION

Materials.

2M AlMe₃ in toluene (Aldrich), GaCl₃ (Aldrich), HSO₃Cl (Aldrich), 21 nmnanopowder TiO₂ (Aldrich), 30% H₂O₂ (EMD) were obtained commercially andused as received. The starting material5,10,15-tris(pentafluorophenyl)corrole (H₃tpfc) was prepared based onthe literature method. The solvents pyridine and toluene were dried overa column. Acetone and dichloromethane used were both of reagent andspectroscopic grades depending on the applications. D-Luciferinpotassium salt (Promega), Hoechst 34580 (Invitrogen™), Hoechst 33258(Invitrogen™), Sytox Green (Invitrogen™), and FM® 1-43FX (Invitrogen™)were used as received according to the provider's instruction.

Chemical Preparation.

All preparations were carried out under Ar(g) atmosphere unlessotherwise noted.

1. Corrole Preparation.

Preparation of2,17-bischlorosulfonato-5,10,15-tris(pentafluorophenyl)corrole(H₃tpfc(SO₂Cl)₂; 1) was performed according to the literature procedure.The metallocorroles described in this study were prepared in thefollowing manner.

1.1. Preparation of 1-Al.

To the 20-mL toluene solution of 0.32 g of 1 (0.32 mmol) in a roundbottom flask was added 0.8 mL of 2M AlMe₃ (1.6 mmol) in toluene solutionat an icebath temperature. The solution was stirred for 10 min followedby the addition of 1 mL anhydrous pyridine. The solution was allowed tostir for another 10 min over ice. The reaction was quenched by anaddition of ice chips. The dark green solution was then extracted withCH₂Cl₂ and washed with water. The solvent was removed in vacuo and thedry deep green solid was redissolved in CH₂Cl₂ followed by filtration.The filtrate was brought to dryness to afford the dark green solid(0.098 g, 26% yield). ESI-MS (CH₂Cl₂): m/z: 1014.87 [M-H]⁻ (Calculatedfor C₃₇H₆N₄F₁₅Cl₂S₂O₄Al: 1015.88); ¹H-NMR (400 MHz, acetone-d₆, ppm):δ=9.76 (s, 1H), 9.25 (s, 1H), 8.97 (d, 1H), 8.85 (d, 1H), 8.70 (d, 1H),8.58 (d, 1H); ¹⁹F-NMR (376 MHz, acetone-d6, ppm): −138.7 (d, 4F), −140.0(d, 2F), −156.9 (t, 1F), −157.5 (t, 1F), −158.1 (t, 1F), −164.9 (m, 2F),−165.3 (m, 2F), −167.0 (m, 2F); UV-Vis (toluene:pyridine, 95:5): λmax (εM⁻¹ cm⁻¹)=436 (4.08×10⁴), 625 (7.66×10³) nm.

1.2. Preparation of 1-Ga.

To a heavy-walled Schlenk flask were added 0.20 g of 1 (0.20 mmol) and0.57 g GaCl₃ (3.3 mmol) under Ar(g). The flask was chilled in N₂(1) andevacuated. 15 mL Degassed anhydrous pyridine (15 mL) was added to theflask via vacuum transfer. The flask was subsequently sealed and allowedto warm to room temperature. The reaction vessel was heated to 120° C.for 1 h. The pyridine solution was diluted with CH₂Cl₂ and washed withwater three times. The solution was then filtered through glass wool andpartially concentrated for recrystallization with hexanes overnight. Theproduct was then filtered, dried, and washed with a combination ofacetone, CH₂Cl₂, and toluene. This filtrate collected was brought todryness in vacuo to afford a dark green solid (0.092 g, 38% yield).ESI-MS (CH₂Cl₂:pyridine): m/z: 1056.81 [M-H]⁻ (Calculated forC₃₇H₈N₄F₁₅Cl₂S₂O₄Ga: 1057.82); ¹H-NMR (500 MHz, CD₂Cl₂, ppm): δ=9.99(s), 8.82 (m), 8.73 (m), 8.57 (m); ¹⁹F-NMR (376 MHz, acetone-d₆, ppm):−138.7 (d), −140.0 (d), −156.9 (t), −157.5 (t), −158.1 (t), −164.9 (m),−165.3 (m), −167.0 (m); UVVis (toluene:pyridine, 95:5): λmax (ε M⁻¹cm⁻¹)=429 (1.65×10⁴), 611 (5.61×10³) nm.

2. TiO₂ Surface activation.

To the solid TiO2 nanoparticle (10 g) in a 2.0-L round bottom flask wasadded 1.2 L 30% H₂O₂ solution. The milky colloidal suspension wasstirred under reflux or 5 h. Upon cooling, the off-white solid wasisolated from the H₂O₂ solution by ultracentrifugation at 4° C. andwashed with copious amount of water. The activated TiO₂ nanoparticle(TiO₂—OH) collected was dried in vacuo for 12 h and stored dry in a vialprior to use.

3. Surface Conjugation.

The following general procedure was employed for the conjugation of thecorroles 1,1-Al, and 1-Ga to the activated TiO₂ nanoparticle surface: Tothe mixed solids containing the activated TiO₂ and corrole in a 25-mLround bottom flask was charged with anhydrous pyridine. The suspensionturned green immediately and was stirred under reflux before thereaction was stopped. The resulting green solid was isolated from thegreen solution by centrifugation and washed multiple times withdichloromethane, acetone, and deionized water until the centrifugesupernatant became colorless. The solid remained green, was dried invacuo, and was stored until further use. The detailed preparationprocedure for each corrole nanoconjugate is given as follows:

3.1. Preparation of 1-TiO₂.

To a 25 mL round bottom flask were added 0.32 g TiO₂—OH and 0.028 g of 1(28.1 mmol), which was subsequently cycled with argon and vacuum. Afterestablishment of the inert atmosphere, 8 mL anhydrous pyridine was addedto the flask and the reaction was set to reflux for 2 h. The resultinggreen solid was collected in a manner following the generalcentrifugation and washing procedures outlined above.

3.2. Preparation of 1-Al—TiO₂.

To a 40 mL vial was added 1.18 g TiO₂—OH, which was subsequently cycledwith argon and vacuum. To this flask, was added 5 mL anhydrous pyridine,followed by sonication to ensure even dispersion. In a second flask, wasadded 0.03 g of 1-Al (25.5 mmol) and 7 mL anhydrous pyridine underAr(g). This solution was stirred and then added to the TiO₂—OH precursorvia syringe. The reaction was sealed and allowed to reflux for 2 h afterwhich, the resulting green solid was collected in a manner following thegeneral centrifugation and washing procedures outlined above.

3.3. Preparation of 1-Ga—TiO₂.

To a 40 mL vial was added 0.84 g TiO₂—OH and 0.04 g of 1-Ga (32.8 μmol),which was subsequently cycled with argon and vacuum. After establishmentof the inert atmosphere, 8 mL anhydrous pyridine was added to the flaskand the reaction was set to reflux for 2 h. The resulting green solidwas collected in a manner following the general centrifugation andwashing procedures outlined above.

Spectroscopies.

UV-Vis spectra were either recorded on a Carey 50 spectrophotometer or aHewlett-Packard 8453 diode-array spectrophotometer at room temperaturefrom samples in various solvents. IR spectra were recorded with a SensIRDurascope ATR accessory plate on a Nicolet Magna-IR spectrometer, anuncooled pyroelectric deuterated triglycine sulfate (DTGS) etector, anda KBr beamsplitter. The ¹H and ¹⁹F NMR spectra were recorded on a VarianMercury 300 (300 MHz for 1H; 288 MHz for ¹⁹F) spectrometer. The NMRspectra were analyzed using MestReNova (v. 6.1.1). ¹H NMR measurementswere referenced to internal solvents. Fluorescence spectra were measuredwith a Jobin-Yvonne/SPEX Fluorolog spectrometer (Model FL3-11) equippedwith a Hamamatsu R928 PMT. Samples were excited at λex=405-430 nm (theSoret region), 514 nm, and 600-630 nm (Q-band region) with 2-nmband-passes. The fluorescence was observed from λem=500-800 nm,depending on the excitation wavelength, at 2-nm intervals with 0.5 sintegration times at room temperature.

Relative Fluorescence Quantum Yield Measurements.

The Φem measurements were performed using degassed toluene solutions of1,1-Al, 1-Ga, and tetraphenylporphyrin (as a standard). Samples wereexcited at λex=355 nm and the emission was observed from λem=500-800 nm.The standard tetraphenylporphyrin was excited at λex=514 nm and theemission was observed from λem=500-800 nm. Φem for tetraphenylporphyrinis 0.11.3 All relative fluorescence quantum yields were calculated basedon the corresponding fluorescence spectra of the samples and thestandard according to the equation:

${\Phi_{em}(x)} = \frac{{A_{s} \cdot F_{s} \cdot \eta_{x}^{2}}{\Phi_{em}(s)}}{A_{x} \cdot F_{s} \cdot \eta_{s}^{2}}$

where Φem(s) and Φem(x) are the relative fluorescence quantum yield ofthe standard and sample, respectively; As and Ax are the absorbance atthe excitation wavelength for the standard and sample, respectively; Fsand Fx are the area under the corrected emission curve for the standardand sample, respectively; and ηs and ηx are the refractive index of thesolvent used for the standard and sample, respectively.

Mass Spectrometry.

Samples were analyzed by direct infusion ESI in the negative ion modeusing an LCT Premier XE (Waters) ESI-TOF mass spectrometer operated inthe W configuration. The samples were prepared in CH₂Cl₂:isopropanol(9:1 v/v) at 10 μM and infused with an external syringe pump at 25μL/min. Some samples contained 50 μL pyridine in 1 mL CH₂Cl₂:isopropanolmixture.

Surface Characterization.

X-ray photoelectron spectroscopy was performed on an M-Probespectrometer that was interfaced to a computer running the ESCA2005(Service Physics) software. The monochromatic X-ray source was the1486.6 eV Al Kα line, directed at 35° to the sample surface. Emittedphotoelectrons were collected by a hemispherical analyzer that wasmounted at an angle of 35° with respect to the sample surface.Low-resolution survey spectra were acquired between binding energies of1 and 1100 eV. Higher-resolution detailed scans, with a resolution of0.8 eV, were collected on the F(1s) XPS line. All binding energies arereported in electronvolts.

Attenuated total reflectance (ATR) infrared spectra of powderedcorrole-TiO₂ nanoconjugate samples were collected using a SensIRDurascope ATR accessory plate on a Nicolet Magna-IR spectrometer, anuncooled pyroelectric deuterated triglycine sulfate (DTGS) detector witha KBr window (400-4000 cm⁻¹), and a KBr beamsplitter. The spectralresolution was 4 cm⁻¹ and 64 scans were collected per spectrum. A KBrbackground spectrum was subtracted from the measured spectrum of thenanoconjugates to provide the desired FTIR characterization data. SeeFIGS. 8 and 9.

Confocal Microscopy.

The phantom imaging experiments were performed using a Zeiss LSM 710Confocal Microscope (Carl Zeiss, Wake Forest, N.C.). The microscopesystem consists of a Zeiss 710 confocal scanner, 63×/1.4 Plan-APOCHROMAToil immersion lens (Zeiss), Axio Observer Z1 microscope and diode-pumpsolid-state lasers. Two visible excitation lines (405 and 561 nm) wereused for the experiments. The microscope is equipped with a QUASAR 32channel spectral detector (two standard PMTs and a 32 channel PMT array)with spectral resolution of 9.7 nm. The software ZEN 2009 was used forhardware control. The laser power used for the experiments is 10% of thetotal available power (25 mW). ImageJ software was employed to processthe resulting data.

Transmission Electron Microscopy.

The morphologies of the TiO2 nanoparticles before and after surfacefunctionalization were imaged using a FEI Tecnai F30ST transmissionelectron microscope (TEM) operated at acceleration voltage of 300 kV.Images were recorded using a Gatan CCD camera. For TEM analysis, a smallquantity of TiO₂ particles was dispersed in IPA by sonication. Thedispersions were drop-cast onto C-Flat™ holey carbon films on a 200 meshCu TEM grid (purchased from Electron Microscopy Sciences).

Approximation of Loading of 1-al on TiO₂ Surface.

Calculation of the corrole 1-Al's loading on the surface of TiO₂ wasbased on the absorbance values obtained from the integrated sphereelectronic absorption measurements described as follows.

Absorption Spectroscopy.

Thin film transflectance measurements were used to calculate the dyeloading on the TiO₂ nanoparticles. Both peroxide-etched anddye-functionalized nanoparticles were dispersed in apolydimethylsiloxane (PDMS) polymer matrix. The weights of the TiO₂nanoparticles, PDMS base (Sylgard® 184 silicone elastomer base from DowCorning), and curing agent (Sylgard® 184 silicone elastomer curing agentfrom Dow Corning) are provided in Table 1 below. The nanoparticles werefirst dispersed in a minimal amount of isopropanol (IPA) by sonication.The dispersion of TiO₂ nanoparticles in IPA was then mixed with the PDMSbase and curing agent using a Vortex mixer. The mixtures were cast intofilms onto quartz substrates and allowed to cure in air for 12 hoursfollowed by curing in a drying oven at 60° for 2 hours. See FIG. 3.

TABLE 1 Weights of TiO₂ nanoparticles, weights of the PDMS base andcuring agnet used to case PDMS films, weight % TiO₂ in the films, filmweight, and mass of TiO₂ per volume of PDMS. Mass Est. dry Mass MassPDMS Total film Film Mass TiO₂/ TiO₂ Mass PDMS curing weight weightWeight weight volume PDMS Sample (mg) IPA (g) base (g) agent (g) (g)(g)^(a) % TiO₂ (g) (g/L)^(b) Etched 3.35 3.683 0.9266 0.1220 1.42031.0593 0.32 0.2901 3.3 TiO₂ 1-Al—TiO₂ 3.25 3.234 0.9425 0.1154 1.38461.0676 0.30 0.3384 3.2 ^(a)Separate measurements showed that 98% of theIPA evaporated during curing of the PDMS film. ^(b)A value of 0.965g/cm³ was used for the density of PDMS.

Transflectance spectra of the etched and dye-functionalized TiO₂nanoparticle films were measured using a Cary 5000 UV-Vis-NIRspectrometer from Agilent Technologies equipped with an integratingsphere (External DRA 1800), a PMT detector, a quartz-iodine lamp for thevisible region (350-800 nm), and a deuterium lamp for the ultravioletregion (300-350 nm). Because the TiO₂ nanoparticles cause diffusescattering of the incident illumination, the PDMS films were placed inthe center of the integrating sphere such that both the transmitted, T,and the reflected, R, (including the spectrally reflected and diffuselyscattered light) light were collected by the PMT detector. Thetransflectance measurements allow for the absorbance, A, of the films tobe determined by A=−log(T+R). The concentration, C, of the dye withinthe PDMS films was then calculated using the Beer-Lambert law, A=εCl,where ε is the extinction coefficient of the dye and 1 is the filmthickness (determined by profilometry, see below). The absorbance valuesat 426 and 595 nm (corresponding to the Soret and Q bands of the dye,respectively) for the PDMS film containing the dye-functionalized TiO₂nanoparticles, the estimated extinction coefficients of the dye at thesewavelengths, and the film thicknesses are provided in Table 2 below. Theabsorbance values for the PDMS film containing the unfunctionalized,peroxide-etched TiO₂ nanoparticles at these wavelengths are alsoprovided, which were subtracted from the absorbance values of thedye-functionalized TiO₂ nanoparticles. The dyeloading was determined tobe between 2.3 and 3.5 μmole of dye per grams of TiO₂ (based on whetherthe Soret or Q band was used to determine the dye concentration).

TABLE 2 Absorption values at 426 and 595 nm and thicknesses for PDMSfilms containing dyefunctionalized and peroxide-etched TiO₂nanoparticles, and estimated dye loading of the TiO₂ particles based onabsorption measurements. Dye- Est. dye functionalized Film extinctionFilm Dye Dye loading Wavelength TiO₂ thickness coefficient Etched TiO₂thickness concentration (μmoles of dye/g (nm) absorbance (cm)(M⁻¹cm⁻¹)^(a) absorbance (cm) (M) of TiO₂) 426 0.170 0.054 4.08 × 10⁴0.005 0.054 7.5 × 10⁻⁵ 2.3 595 0.048 0.054 7.66 × 10³ 0.002 0.054 1.1 ×10⁻⁴ 3.5 ^(a)Extinction coefficients measured in toluene:pyridine (95:5)mixture.

Profilometry.

Thickness profiles of the PDMS films were measured using a BrukerDektakXT stylus surface profilometer. The diameter of the diamond-tippedstylus was 2 μm and a weight of 1 mg was applied to the film,respectively. The stylus was scanned at a rate of 250 μm/s. Thethickness profiles were used measure the average path length through thePDMS films during the transflectance measurements.

Cell Culture and Cell Viability Assay.

Pathogen-free U87-LUC cell line (TSRI Small Animal Imaging and ResearchLaboratory) was grown in 75 mL flask in Dulbecco's Minumal EssentialMedium (DMEM) in 5% CO₂ at 37° C. The cell culture medium wassupplemented with 10% fetal bovine serum (FBS) and 1% the antibioticprimocin. The cell culture medium was replenished every two days and thecells were passaged once they reached 80% confluence. Primary mousehepatocytes (PMH) were isolated and cultured as previously described.

For U87-Luc cell culture experiments. The cells were plated in an8-chamber slide (Cultureslide, BD) were treated with 1-Al—TiO2 suspendedin PBS over a range of 2 ng/mL to 2 mg/mL. A primary stock solution (6.3mg 1-Al—TiO₂ in 1 mL PBS) was prepared. The primary stock solution wasfurther diluted to prepare secondary and tertiary stock solutions. Thevarious amount of stock solutions were added to the eight-well glassslide plated with cells to give the aforementioned range ofconcentrations. The final volume for each well is 300 μL. Aftertreatment, the treated cells and controls were incubated in the dark in5% CO₂ at 37° C. for a period of 24, 48, and 72 h. The cells were imagedusing the cooled IVIS® animal imaging system (Xenogen, Alameda, Calif.USA) linked to a PC running with Living Image™ software (Xenogen) alongwith IGOR (Wavemetrics, Seattle, Wash., USA) under Microsoft® Windows®2000. This system yields high signal-to-noise images of luciferasesignals emerging from the cells. Before imaging, 0.5 mL of 150 mg/mLluciferin in normal saline was added to each well. An integration timeof 1 min with binning of 5 min was used for luminescent imageacquisition. The signal intensity was quantified as the flux of alldetected photon counts within each well using the LivingImage softwarepackage. All experiments were performed in triplicate.

For PMH cell culture experiments, the cells were plated in a 6-chamberslide (Cultureslide, BD). After three hours, media was exchanged(DMEM-F12) and the cells were treated with 1-Al—TiO₂ suspended in PBSover a range of 0.3 ng/mL to 0.3 mg/mL. A primary stock solution (6.3 mg1-Al—TiO₂ in 1 mL PBS) was prepared. The primary stock solution wasfurther diluted to prepare secondary and tertiary stock solutions. Thevarious amount of stock solutions were added to the eight-well glassslide plated with cells to give the aforementioned range ofconcentrations. The final volume for each well is 2000 μL. After 24 or48 h of treatment, cells were double stained with Hoechst 33258 (8mg/mL) and Sytox Green (1 mmol/L). Quantitation of total and necroticcells (Sytox Green positive) was performed by counting cells in at least5 different fields using ImageJ, as previously described. Allexperiments were done in triplicate.

In Vitro Confocal Fluorescence Microscopy.

The U87-Luc cells were seeded at 20,000 cells per well on an 8-chamberslide (Cultureslide, BD) and allowed to grow overnight. Cells werewashed with PBS and were incubated in serum free media mixed 1:1 with1-Al—TiO₂ for 24, 48, and 72 h at 37° C. over the concentration rangesimilar to the U87-Luc cell viability assay (2 ng/mL to 2 mg/mL). Cellswere then washed 3× with PBS and stained with Hoechst 33258 and FM®1-43FX stains. The cells were chilled on iced and then imaged withoutbeing fixed using a Zeiss LSM 710 inverted confocal microscope.

Electronic absorption spectra for 1,1-Al, and 1-Ga was obtained indegassed toluene. Solutions reveal the signature Soret and Q-bands forthese tetrapyrrolic macrocycles (FIG. 1). The electronic absorption datafor the chlorosulfonated corroles are also given in Table 3.

TABLE 3 Electronic spectroscopic data for chlorosulfonated corroles 1,1-Al, and 1-Ga in toluene solution Electronic Fluorescence^(a)Absorption^(a) λ_(ex) λ_(ex) Corrole λ_(max) ^(b) (nm) (nm) (nm) φ_(em)^(c) 1 430 (S) 426 670 0.094 580 (Q) 1-Al 424 (S) 420 611 0.127 592 (Q)1-Ga 426 (S) 427 609 0.099 588 (Q) ^(a)The measurements were performedin degassed toluene. ^(b)The maximum absorption wavelengths are reportedfor both Soret (S) and Q-bands (Q). ^(c)The relative emission quantumyields were determined using tetraphenylporphyrin as a standard.

The electronic absorption spectra of the colloidal suspensions of1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ nanoconjugates in PBS pH 7.4 revealmaximum absorptions centered around 425 and 600 nm for the Soret andQ-bands, respectively (Table 4).

TABLE 4 Electronic absorption, vibrational, and X-ray photoelectronspectroscopic data for corrole-TiO₂ nanoconjugates 1-TiO₂, 1-Al— TiO₂,and 1-Ga—TiO₂ Electronic SO₂ Vibrational Absorption Frequency (cm⁻¹)F(1s) Binding Conjugate λ_(max) (nm) Sym Asym Energy (eV) 1-TiO₂ 415,430 (S) 1153 1410 691 591, 621 (Q) 1-Al—TiO₂ 427 (S) 1244 1431 690 576,610 (Q) 1-Ga—TiO₂ 423 (S) 1160 1450 688 589, 610 (Q)

These peak maxima are in agreement with the spectroscopic properties ofthe corresponding molecular corrole (Table 3). The Soret band splittingfor 1-TiO₂ is similar to the splitting observed for its amphiphilicmolecular counterpart2,17-bissulfonato-5,10,15-tris(pentafluorophenyl)corrole in an aqueoussolution at physiologic pH, supporting the presence of the sulfonatelinkage on the corrole anchored to TiO₂ surfaces. The splitting pattern,however, was not observed for the metalloconjugates 1-Al—TiO₂ and1-Ga—TiO₂, owning to the presence of metal bound to deprotonatednitrogen atoms.

Characterization of the fine green powder of 1-TiO₂, 1-Al—TiO₂, and1-Ga—TiO₂ with FT-IR spectroscopy reveals vibrational absorption bandsaround 1180-1250 cm⁻¹ assigned to the symmetric stretching of SO₂ groupsas well as those around 1400-1450 cm⁻¹ assigned to asymmetric stretchingof SO₂ groups of covalent sulfonates. The presence of these vibrationalsignatures suggests that the corroles are covalently attached to thesurface of TiO₂ through a sulfonate linkage. The vibrational frequenciesfor these TiO₂-corrole nanoconjugates are listed in Table 2. X-rayphotoelectron spectroscopy was performed to study the elemental presenceof the surface of the nanoparticle conjugates (Table 4). High-resolutionscans for the spectra of the conjugates revealed F(1s) binding energypeaks between 688 and 691 eV, suggesting the presence of correspondingpentafluorophenyl corroles attached to the TiO₂ surface. See FIG. 10.

Confocal fluorescence microscopy images of aggregates of thenanoconjugates 1-TiO₂, 1-Al—TiO₂, and 1-Ga—TiO₂ in the solid state(FIG. 1) were taken with the samples illuminated at λ_(ex)=405 nm andthe λ_(em) recorded from 508 to 722 nm. The images for 1-Al—TiO₂ and1-Ga—TiO₂ (FIGS. 1 e and 1 h) exhibit fluorescence areas on thenanoparticles compared to the relatively darker image for 1-TiO₂. Thefluorescence signals observed with various intensities across the TiO₂samples for 1-Al—TiO₂ and 1-Ga—TiO₂ also suggest that the TiO₂ surfacesare not evenly functionalized because of material aggregation. Selectedfluorescence areas (white circles) on all three images, spectralprofiles representing the nanoconjugates 1-TiO₂, 1-Al—TiO₂, and1-Ga—TiO₂ were obtained (FIGS. 1 c, 1 f, and 1 i). These spectralprofiles and fluorescence signal intensities are in agreement with thefluorescence spectra (FIGS. 1 a, 1 d, and 1 g) obtained from themolecular corroles 1, 1-Al, and 1-Ga.

The nanoconjugate 1-Al—TiO₂ was chosen as a candidate for cellularuptake and cytotoxic effect studies. The TEM images of TiO₂ (FIG. 2)show the average particle size to be 29 nm, post-corrolefunctionalization, albeit, they appear to aggregate. Images were takenfor both before and after surface functionalization as well as for bothbefore and after H₂O₂-etching. Absorption measurements of the particlesembedded in a transparent polymer matrix, facilitated with the use of anintegrating sphere, indicate nearly identical absorption features in themolecular and conjugated species. These experiments afforded anapproximate loading of 1-Al on the surfaces of ca. 10-40 mg/g TiO₂.(FIG. 2).

Treatment of the luciferase-transfected glioblastoma cell U87-Luc with awide range of 1-Al—TiO₂ concentrations (2 ng/mL to 2 mg/mL) revealsinternalization of these nanocojugates over a period of 24, 48, and 72 has shown by the confocal fluorescence microscopic (CFM) images (FIG. 4).

The CFM images were taken after the cells were stained with the nuclearand cell membrane dyes, and washed with the media solution several timesto remove the excess dyes and 1-Al—TiO2 nanoconjugates. The nucleuslabeled with a Hoechst stain is seen in bluish purple (λex=405 nm,λem=460 nm). The membrane seen in green is labeled with the dye FM®1-43FX (λex=488 nm, λem=580 nm). The nanoconjugate 1-Al—TiO₂ is observedin red (λex=405 nm, λem=634 nm).

The Z-stacked confocal fluorescence microscopic (CFM) images (FIG. 5) ofU87-Luc cells treated with similar concentrations (2 ng/mL to 2 mg/mL)of 1-Al—TiO₂ for 48 and 72 h from three different perspectives are alsoshown (FIG. 5). The Z-stacked CFM images of individual cells were takenat 0.5-1 μm slice intervals from top to bottom.

The 1-Al—TiO₂ nanoconstruct could also be internalized throughendocytosis. Based on the confocal fluorescence images, thenanomaterials 1-Al-modified TiO₂ is suspended in the cytosol as opposedto the modified TiO₂ labeled with alizarin red S, which showedperinuclear localization in HeLa cells. These findings suggest adistribution pattern of the TiO₂ nanoconjugates within the cells similarto another study, in which 1-D TiO₂ nanorods and nanoparticles labeledwith fluorescein thiocyanate were internalized into HeLa cells after agiven period of time. The internalization of 1-Al—TiO₂ into glioblastomacells can also be observed even at a very low concentration range(<μg/mL).

TiO₂ nanoparticles exhibit various degrees of cytotoxic activities uponphotoactivation by UV-Vis light leading to formation of reactive oxygenspecies. To best study and understand the cytotoxic effect of the1-Al—TiO₂ conjugate that is not related to the photocatalytic propertyof TiO₂ on cell death, the glioblastoma cell U87-Luc was treated in theabsence of UV-Vis irradiation with the same range of 1-Al—TiO₂concentrations (2 ng/mL to 2 mg/mL) as in the cell internalizationstudies. The cells were incubated over a period of 24, 48, and 72 hprior to bioluminescence cell viability assays. Based on thebioluminescence signal of the firefly luciferin from living U87-Luccells, which is related to the level of cellular ATP, the cytotoxicassay shows that the nanoconjugate 1-Al—TiO₂ has essentially nocytotoxic effect on the glioblastoma cells after 24 h of treatment (FIG.6) and, therefore, could be considered biocompatible. On the other hand,the cytotoxic effect becomes more apparent as the cells were exposed tothe corrole-TiO₂ nanoparticles for extended periods of time at higherconcentrations (>200 μg/mL). For example, only ca. 65% and ca. 30% ofthe bioluminescence signals from the live cells were observed after the48-h and 72-h treatments at 2 mg/mL, respectively. This viability studyof the U87-Luc cells treated with 1-Al—TiO₂ is also consistent with astudy performed on mouse fibroblast cells, using the MTT assay, showingthat the cytotoxic effects of TiO₂ at various concentrations (3 to 600μg/mL) were negligible after 24 h of treatment whereas the 48-htreatment of these cells with the nanoparticle showed decrease in cellviability at higher concentrations. Another study on the cytotoxicityeffect of unmodified 1-D and 3-D TiO₂ on HeLa cell also show that thesenanoparticles were relatively nontoxic at concentrations up to 125 μg/mLin the absence of light.

Additionally, to compare the cytotoxic effect of the nanoconjugate1-Al—TiO₂ on cancer and normal cells, mouse primary hepatocytes (MPH)were treated with 1-Al—TiO₂ in various concentrations (0.3 ng/mL to 0.3mg/mL) for 24 and 48 h (FIG. 7). It was observed that 1-Al—TiO₂ was alsoessentially nontoxic up to 3 mg/mL after both 24 and 48 h of treatment.Only at higher concentrations were the ratios of the live cells droppedbelow 80%. The MPH behave similarly after 24-h and 48-h treatments withvarious doses of 1-Al—TiO₂, suggesting that low 1-Al—TiO₂ concentrationshave minimal cytotoxic effects on the viability of these normal cells.While the trend at high concentrations were not observed for theglioblastoma U870-Luc cells treated with 1-Al—TiO₂, it is expected thatnormal cells, especially primary cells, are less tolerant towardsexogenous non-native agents. Nonetheless, the intense fluorescenceexhibited by 1-Al would allow for the use of the nanoconjugate 1-Al—TiO₂as an optical imaging agent observable by confocal fluorescencemicroscopy even at low concentrations (20-200 ng/mL) below the cytotoxicthresholds for both the cancer and normal cells observed in the studies.

4-(chlorosulfonyl)Benzoic Acid+TiO₂ (Anatase)

Added TiO₂ (0.1099 g) and 4-(chlorosulfonyl)Benzoic Acid (0.0171 g) toscintillation vial. Pumped into dry box. Added anhydrous Pyridine (3 mL)and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed tocool to room temperature, then added 2 mL H₂O, which then centrifugeddown. Washed and centrifuged with acetone, acetone, water, and acetone.Pumped down on high vacuum line to afford product for InfraredSpectroscopy.

Biphenyl-4-sulfonyl Chloride+TiO₂ (Anatase)

Added TiO₂ (0.1253 g) and Biphenyl-4-sulfonyl Chloride (0.0208 g) toscintillation vial. Pumped into dry box. Added anhydrous Pyridine (3 mL)and heated to 120° C. for 1 hr, under an inert atmosphere. Allowed tocool to room temperature, then added 2 mL H₂O, which then centrifugeddown. Washed and centrifuged with acetone, acetone, water, and acetone.Pumped down on high vacuum line to afford product for InfraredSpectroscopy.

4′-chlorobiphenyl-4-sulfonyl Chloride+TiO₂ (Anatase)

Added TiO₂ (0.1205 g) and 4′-chlorobiphenyl-4-sulfonyl Chloride (0.0210g) to scintillation vial. Pumped into dry box. Added anhydrous Pyridine(3 mL) and heated to 120° C. for 1 hr, under an inert atmosphere.Allowed to cool to room temperature, then added 2 mL H₂O, which thencentrifuged down. Washed and centrifuged with acetone, acetone, water,and acetone. Pumped down on high vacuum line to afford product forInfrared Spectroscopy.

Chlorsulfonyl Isocyante +TiO₂ (Anatase)

Added TiO₂ (0.1205 g) to scintillation vial. Pumped into dry box. Added100 μL Chlorsulfonyl Isocyante. Added anhydrous Pyridine (3 mL) andheated to 120° C. for 1 hr, under an inert atmosphere. Allowed to coolto room temperature, then added 2 mL H₂O, which then centrifuged down.Washed and centrifuged with acetone, acetone, water, and acetone. Pumpeddown on high vacuum line to afford product for Infrared Spectroscopy.

Chlorsulfonyl Isocyante +TiO₂ (Anatase)

Added TiO₂ (0.1269 g) to scintillation vial. Pumped into dry box. Added400 μL Chlorsulfonyl Isocyante. Heated to 120° C. for 1 hr, under aninert atmosphere. Allowed to cool to room temperature, then added 4 mLH₂O, which was then centrifuged down. Washed and centrifuged withacetone, acetone, water, and acetone. Pumped down on high vacuum line toafford product for Infrared Spectroscopy.

According to the methods described herein, other Cl—SO₂-containingsubstrates can also be employed, such as, for example, 2-pentyl sulfonylchloride, 3,3,3-trifluoropropane-1-sulfonyl chloride,methyl(chlorosulfonyl)acetate, and the like.

What is claimed:
 1. A material according to formula II

wherein B is —NCO, C₁₋₁₀alkyl, or

wherein R¹ is —COOH, —COOC₁₋₆alkyl, C₁₋₆alkyl, or aryl optionallysubstituted with halogen or C₁₋₆alkyl; M is a surface comprising TiO₂,BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO,Mn₂O₃, MnO₂, NiO, SnO, SiO₂, BaTiO₃, or ZnO; and n is 0 or
 1. 2. Thematerial according to claim 1, wherein the surface is a nanoparticlesurface.
 3. The material according to claim 1, wherein B is —NCO.
 4. Thematerial according to claim 1, wherein B is


5. The material according to claim 4, wherein B is


6. The material according to claim 1, wherein n is
 0. 7. The materialaccording to claim 1, wherein n is
 1. 8. A method of making a materialaccording to claim 1 comprising contacting a surface comprising TiO₂,BaTiO₃, SnO₂, Al₂O₃, Fe₂O₃, Fe₃O₄, ZrO₂, CeO₂, CdO, Cr₂O₃, CuO, MnO,Mn₂O₃, MnO₂, NiO, SnO, SiO₂, or ZnO, the surface having at least one —OHgroup; with a compound of formula IV:Cl—SO₂—R  (IV) wherein R is —NCO, C₁₋₆alkyl, or

wherein R¹ is —C(O)OH, —C(O)OC₁₋₆alkyl, C₁₋₆alkyl, or aryl optionallysubstituted with halogen or C₁₋₆alkyl.
 9. The method of claim 8, whereinthe surface is a nanoparticle surface.
 10. The method of claim 8,wherein B is —NCO.
 11. The method according to claim 8, wherein B is


12. The method according to claim 11, wherein B is


13. The method according claim 8, wherein n is
 0. 14. The methodaccording to claim 8, wherein n is 1.